On 3 August 1914, Dennis and his wife learned of the outbreak of war in Europe. Prompt measures were reported to be underway to guard Nigeria’s frontier on the side of the German Cameroons (LH 3 & 5 August 1914). Dennis visited the Commissioner at Owerri for further news and reflected that the situation appeared likely to bring suffering beyond anything previously known in world history. Planned travel for October was uncertain and depended on the progress of naval fighting in the coming weeks. On 6 August, troops stationed at Owerri departed early in the morning for Calabar.
The following Tuesday, the Commissioner sent additional war news. The Karina had been stopped in the Bay of Biscay by French warships, and German Togoland had been taken without any fighting. Two days later, Dennis learned that five German cruisers were in the Atlantic and wondered whether any might reach the West Coast. The Commissioner and his wife visited them the next day.
On 21 January, Dennis received details from Onitsha of a cable from the Provincial Commissioner stating that no CMS missionaries were to return to England from Nigeria except under urgent necessity. The war situation continued to deteriorate, making sea travel dangerous and increasingly restricted. Reports were received of Germany’s declared intention to pursue a ruthless submarine campaign, believed to be more severe than anything previously attempted.
Dennis and his wife questioned whether they would be able to return to England in June. In addition to a cablegram from Salisbury Square, the CMS headquarters, urging that no missionaries travel to England except for urgent reasons, local Government authorities notified them that no women or children were permitted to leave for England except in cases of illness, urgent family reasons, or to undertake war work.
The following week, Dennis wrote that they would plan to return at the end of June if the decision rested with them. He noted that they were seeking divine guidance, acknowledging that they might be prevented from traveling by either local Government authorities or CMS authorities in London. He asked for prayers regarding their decision (LH 16 February 1917).